CVE-2026-89991

UNRATEDCVSS · not yet scoredTrending — 3 sources updated this week
—
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No CVSS published and no exploitation signals yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS v2: —Exploit: None knownExposed services: Not assessed

No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.

In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix infinite loop in pcpu_freelist push with one possible CPU

__pcpu_freelist_push() can loop forever when only one CPU is possible and an NMI re-enters pcpu_freelist_push() while the interrupted context holds that CPU's freelist lock.

After the current-CPU fast path fails, the fallback loop walks cpu_possible_mask while skipping the current CPU. With CONFIG_SMP=n, or when an SMP kernel is limited to one possible CPU with nr_cpus=1 or possible_cpus=1, there are no other possible CPUs to examine. The loop therefore makes no lock acquisition attempt and can never make progress.

The following stack was observed on a UP system:

NMI context: pcpu_freelist_push free_htab_elem htab_map_delete_elem [perf-event BPF program] __perf_event_overflow perf_event_nmi_handler exc_nmi

Interrupted context: __pcpu_freelist_push pcpu_freelist_push free_htab_elem htab_map_delete_elem [raw_tp/sys_enter BPF program] __bpf_trace_sys_enter do_syscall_64

raw_res_spin_lock() detects the same-CPU recursive acquisition and returns -EDEADLK, but the subsequent fallback loop has no candidate head on a system with one possible CPU.

Restore the extra fallback head that existed before the rqspinlock conversion. Keep the current-CPU fast path, then try the other possible CPUs and finally the extra head. The additional head lets a push, which cannot fail without losing a preallocated element, make progress when the only per-CPU head is held by the interrupted context.

Also check the extra head from the pop path so that nodes placed there can be reused.

CVSS v3
—
EchelonGraph score
Not yet assessedNo source has published severity data for this CVE yet — no CVSS score from NVD or a CNA, no GitHub advisory, and it is not in CISA KEV. This is not a rating of zero; we cannot assess it yet.
EG Score
—
EG Risk
—
EPSS PROB
0.2%
EPSS %ILE
9th
KEV
Not listed

Published

September 16, 2026

Last Modified

September 16, 2026

References (3)

Vendor Advisories for CVE-2026-89991(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.2~rc7-1~exp1 (178 versions)
  • every version up to 7.2.6-1: fixed in 7.2.6-1
—

Data Freshness Timeline

(refreshed 8× in last 7d / 24× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-04 23:22 UTCEPSS rescore
  2. 2026-10-02 16:29 UTCGHSA enrichment
  3. 2026-10-01 19:51 UTCEPSS rescore
  4. 2026-09-30 15:04 UTCEPSS rescore
  5. 2026-09-29 10:45 UTCEG score recompute
  6. 2026-09-29 10:45 UTCGHSA enrichment
  7. 2026-09-28 13:52 UTCEPSS rescore
  8. 2026-09-28 13:52 UTCEPSS rescore
  9. 2026-09-27 13:49 UTCEPSS rescore
  10. 2026-09-26 15:59 UTCEPSS rescore
  11. 2026-09-26 04:41 UTCGHSA enrichment
  12. 2026-09-24 14:04 UTCEPSS rescore
  13. 2026-09-23 17:54 UTCEPSS rescore
  14. 2026-09-22 22:48 UTCGHSA enrichment
  15. 2026-09-22 16:01 UTCEPSS rescore
  16. 2026-09-21 21:09 UTCEPSS rescore
  17. 2026-09-20 20:16 UTCEPSS rescore
  18. 2026-09-19 17:05 UTCEG score recompute
  19. 2026-09-19 17:05 UTCGHSA enrichment
  20. 2026-09-18 19:28 UTCEPSS rescore
  21. 2026-09-17 19:32 UTCEPSS rescore
  22. 2026-09-16 11:21 UTCNVD update
  23. 2026-09-16 10:38 UTCEG score recompute
  24. 2026-09-16 10:36 UTCMITRE cvelistV5first tracked

Frequently asked(4)

What is CVE-2026-89991?
CVE-2026-89991 is a publicly disclosed vulnerability published on September 16, 2026. In the Linux kernel, the following vulnerability has been resolved: bpf: Fix infinite loop in pcpu_freelist push with one possible CPU pcpufreelistpush() can loop forever when only one CPU is possible and an NMI re-enters pcpufreelistpush() while the interrupted context holds that CPU's freelist…
When was CVE-2026-89991 disclosed?
CVE-2026-89991 was first published on September 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-89991 actively exploited?
CVE-2026-89991 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (9th percentile of EPSS-scored CVEs).
How do I remediate CVE-2026-89991?
No fix for CVE-2026-89991 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-89991 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-89991

Explore →

Is Your Infrastructure Affected by CVE-2026-89991?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs